A variety of different types of mobile communication systems have been developed and deployed and are regularly utilized for communication. And, for many, ready access to a mobile communication system to communicate therethrough is a practical necessity. In a mobile radio communication system, as well as other types of communication systems, data is communicated between a set of communication stations including a sending station and a receiving station by way of a communication channel. In a mobile, or other radio, communication system, the communication channel is defined upon a radio link, part of the electromagnetic spectrum. The communication channel is non-ideal. During communication of the data upon the communication channel, the signal containing the data can become distorted. Additional distortion is sometimes also introduced upon the data once received at a receiving station. If the distortion is significant, the informational content of the data cannot accurately be recovered. Various techniques are provided in order to make compensation for, or otherwise to overcome, the distortion introduced upon the data. Space diversity, for instance, is sometimes provided, either at a sending station or at a receiving station, or both. Space diversity is created at a sending station, for instance, through the use two or more spaced-apart transmit antennas, thereby to provide spatial redundancy. Analogously, at a receiving station, use of two or more receive antennas analogously provides spatial diversity. In a cellular, or other mobile radio, communication system in which mobile stations are used by which to communicate, spatial diversity techniques have conventionally been utilized only at the network part of the communication system.
Use of diversity antennas at a mobile station has been, to date, generally limited. Mobile stations are generally small form-factor devices. Their small physical dimensions limit the use of multiple antennas. Additionally, use of multiple antennas also requires a corresponding increase in RF (Radio Frequency), front-end and base band processing of received data. Increased processor complexity and computational ability is required. Such increases result in a corresponding increase in power dissipation, adversely affecting battery longevity.
However, various advancements in circuit, and other, technologies, have increased the feasibility of use of spatial diversity at a mobile station.
Efforts, therefore, have been directed towards providing spatial diversity to a mobile station. For instance, work related to DARP (Downlink Advanced Receiver Performance) attempts to utilize an advanced receiver in a mobile terminal, having a single antenna, to increase the tolerance of the receive part of the mobile terminal to co-channel interferers. MSRD (Mobile Station Receiver Diversity) requirements are set forth therein for evolved EDGE (Enhanced Data for GSM Evolution) and are based, in part, on the DARP efforts.
Advanced receivers are implementable in various different manners. For instance, such receivers variously include, e.g., Joint Space Time Optimizing Filters (JSTOFs) or Weiner filters, and utilize, e.g., joint detection (JD) techniques. In DARP-related standardizations, envisioned communication signaling pertained primarily to improvements of GMSK (Gaussian Minimum Shift Keying) signaling. For instance, such signaling pertained to GSM (Global System for Mobile Communications) voice services, GPRS (General Packet Radio Service) and the most-robust Modulation and Coding Schemes (MCS) used in EDGE-based communications at lower data interchange speeds, e.g., MCS-1 through MCS-4. Simple extension of the capabilities of DARP requirements to more-complex techniques, such as 8-PSK, 16-ary or 32-ary modulation techniques, used for higher-speed EDGE modulation and coding schemes, are generally envisioned to require, or be improved by the use of multiple RF receivers, amenable for multiple-antenna implementations.
Various issues remain with respect to use of spatial diversity at a small form-factor receive station, such as a mobile station. And, further efforts with respect to implementation of such receiving stations that have spatial diversity is required.
It is in light of this background information related to the use of spatial diversity in communication systems that the significant improvements of the present invention have evolved.